Major Blues scales are six-note scales.
The major-blues scale conforms to the following scale formula:

scale degree [ formula ]

1

2

#2 / b3

3

5

6

solfege syllable

do

re

ri / me

mi

sol

la

key of C [ C major blues ]

C

D

D# / Eb

E

G

A

The major-blues scale contains the root, third and fifth of the major triad (1-3-5), and all four chord-tones of the major-sixth chord (1-3-5-6).
Of the additional tones, scale-degree two is the simple-interval equivalent of tension nine,
which is available as a tension on most major triads, all major-sixth chords, all
major-seventh chords, and many
seventh chords, depending on function.
Scale-degree #2 / b3 is the major-blues scale equivalent of the blue note in the
Blues scale.
This note functions most typically as a chromatic approach from below to the third of the chord or key,
and as a chromatic pseudo passing-tone between the ninth and third of the chord or key,
very typical sounds in music-styles such as country, western-swing, and bluegrass.
The table below shows many of the applications for this scale.

*NOTE: Major Blues scales and Major Pentatonic scales are virtually always compatible; where one works, so will the other.
The overlay relationships are more sensitive. Experimentation is recommended.